This is the temperature of the air inside a tunnel, trough or channel. The same approach is used for air-filled pipes with ducts.

Symbol
$\theta_{at}$
Unit
°C
Formulae
 $iteration$ in tunnel $\left(1-\lambda_t\right) \theta_{at,i}+\lambda_t \left(\theta_{at,0}+\Delta \theta_{air}\right)$ in trough or channel $\left(1-\lambda_t\right) \theta_{at,i}+\lambda_t \theta_{at,0}$ in air-filled pipe with ducts
Related
$\Delta \theta_{air}$
$\theta_{at,0}$
$\theta_{at,i}$
Used in
$\Delta \theta_s$
$I_c$
$k_{air}$
$\nu_{air}$
$p_{atm}$
$\mathrm{Pr}_{air}$
$T_{sa}$
$\theta_c$
$\theta_{de}$
$\theta_e$
$\theta_{hs}$
$\theta_{tm}$
$W_{hs}$